Devices for illuminating and inspecting container bottoms are known and adequately described in the prior art. EP 0 894 544 A discloses an inspection machine in which the containers, in this case bottles, are conveyed in a suspended manner above an illuminating device. The illuminating device itself is a cuboid-shaped block that shines through the bottles from below. In principle, these devices are proven and suitable. But they have to be cleaned relatively frequently in order to ensure reliable operation and meaningful measured values.
DE 10 2005 057 872 A1 proposes producing the conveyor, which is illuminated from below and on which the bottles to be inspected stand, so as to be transparent and in the form of a turntable. This reduces the contamination on the illuminating unit itself. But solid and liquid adhesions on the transparent turntable itself also require regular cleaning.